I think the most six common pose mistakes are in:
1) Warrior one,
3) Forward bending with the pray position of hands in the back
4) Down dog,
6) Forward bending (Uthanasana).
In Warrior One the usual mistake that people do is that they are trying to put the hip square while the knee, ankle, and foot are facing to the side. I believe that as a beginner or even if there is not enough flexibility in the ankle or leg there is no point or create this stress to the leg to square the hip. The people should know that the principal thing to move the hip in this asana is connected with the movement of the whole leg. In this case, the student would prefer to have the ankle flexed facing the same side that the hip with the toes on the floor, so the knee is the release of the twist.
In Trikonasana and the asana with Forward bending with the hands in pay position in the back have the same mistake with the previous one, however in this case there is necessary to understand that the hip need space between our leg to twist or to have the hips square. In this pose is important to have a small gap between the legs to fold forward and to be able to twist. Likewise in this pose apply the same principals of the Warrior One posture, the position of the foot, ankle and knee are essential in the hip alignment.
In Down Dog posture the mistake is mainly the overextension on the back, with creates compression in the scapula, shoulders, and neck. The student must be lengthening the spine instead of having extension or hyperextension.
In the Cobra Asana, the people usually use the hands to lift their chest up and create compression on the lower back. This happened as a consequence of not have the spine column lengthening with enough flexibility. Also because the tailbone has to be tuck in towards the floor.
The last posture is the ones that involve Forward Bending, as the student usually bends the spine rounded for the lack of flexibility of the lower back. This happens in uthanasana and some similar to this.
Author: Yogi Chetan Mahesh